Isolation and Characterization of a Novel Toluene-Degrading Bacterium Exhibiting Potential Application in Bioremediation

Background: Toluene is a cyclic aromatic hydrocarbon which is widely used as an industrial feedstock and as a solvent. It is one of the major parts of pollution in oil-contaminated environments. Objectives: The main aim of this study was to isolate and characterize a bacterium with high potential application in toluene bioremediation. Materials and Methods: To isolate a toluene-degrading bacterium, several seawater and wastewater samples were added to toluene-containing basal salt media (BSM). The isolate was identified by morphological features, biochemical tests, and molecular characterization. Also, physiological characteristics of the isolated strain were determined. Results: The isolate represented the capability of growing on toluene under both aerobic and anaerobic conditions. Moreover, this bacterium could also use different toxic compounds as the sole sources of carbon and energy. Sequence analysis of 16S rDNA showed that the isolated strain was closely related to Uncultured bacterium clone A1-E3_M13R (98%) and was submitted as Bacterium Ex-DG74 in NCBI. Bacterium Ex-DG74 showed a tolerance to organic solvent and saline conditions as it could grow in the medium containing over 15% toluene (v/v) and NaCl (w/v), and degraded 79% and 45% of toluene (1% (v/v)) in aerobic and anaerobic conditions, respectively. Conclusions: In this investigation we succeeded to isolate a novel toluene-degrading bacterium from wastewater. This isolated strain could be considered as a biological material for the toluene bioremediation.